The Principal Diagnosis Effect

A sixty-nine year old male is admitted with severe abdominal pain and is found to have diverticulitis. He undergoes an open sigmoidectomy with pathology report revealing a peridiverticular abscess. The patient has other secondary conditions such as COPD, hypertension, Stage II chronic kidney disease, hypothyroidism and GERD. The coder codes K57.32 for the diverticulitis figuring the abscess will not make a difference since with ICD-10-CM diverticulitis with abscess is now a combination code (K57.20). So she does not bother to query the physician regarding the pathology finding of abscess. Grouping the chart under MS-DRGs with the appropriate codes finds the following:

Principal Dx

K57.32

Secondary Dxs

J44.9

I12.9

N18.2

E03.9

K21.9

Principal Procedure

0DTN0ZZ

DRG

331

Weight

1.6623

However, had the coder queried the physician regarding the abscess finding on the pathology report and it was confirmed, the MS-DRG grouping would look like this:

Principal Dx

K57.20

Secondary Dxs

J44.9

I12.9

N18.2

E03.9

K21.9

Principal Procedure

0DTN0ZZ

DRG

330

Weight

2.5405

The above is one example how the reimbursement methodology for Medicare Severity Diagnosis Related Group (MS-DRG) has been affected by the implementation of ICD-10. There are certain codes when assigned as Principal Diagnosis that act as their own complication/comorbidity (CC) or major complication/comorbidity (MCC). Some of these diagnoses include: